1. Field of the Invention
The present invention relates generally to a gas turbine engine, and more specifically to a turbine vane with film cooling holes on the vane endwall.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
In a gas turbine engine, the turbine section includes a multiple stages of rotor blades and stator vanes to guide the hot gas stream through the turbine and convert the hot gas flow into mechanical energy by rotating the shaft. Since the engine efficiency can be increased by passing a higher hot gas flow through the turbine, it is an important design factor to make the airfoils (blades and vanes) from the highest resistant material that will withstand the high stresses and high temperatures. It is also an important design factor to provide effective cooling with a minimal amount of cooling air since the cooling air is pressurized air from the engine compressor that is wasted and therefore will also decrease the efficiency of the engine.
The stator vanes (sometimes referred to as guide vanes or nozzles) 11 include endwalls 12 on the inner and outer ends of the vanes that form hot gas flow paths through the vanes. The stator vanes require film cooling on the airfoil part and the endwall part to prevent thermal damage. Prior art vane endwall leading edge region is cooled with a double row of circular or shaped film cooling holes 13 as seen in FIG. 1. As a result of this prior art film cooling hole arrangement, streamwise and circumferential cooling flow control due to the airfoil external hot gas temperature and pressure variation is difficult to achieve. Film cooling air discharged from the double film rows have a tendency to migrate from the pressure side toward the vane suction side surface which will induce an uneven distribution of film cooling flow and endwall metal temperature.
It is an object of the present invention to provide for a turbine vane endwall leading edge region with improved leading edge film cooling to reduce the endwall metal temperature and reduce the cooling flow requirement.